Neutrophil Chemotaxis Chasing a Bacterium

Neutrophil granulocytes, generally referred to as neutrophils, are the most abundant type of white blood cells in humans and form an essential part of the immune system. They form part of the polymorphonuclear cell family (PMN's) together with basophils and eosinophils.

Neutrophils are normally found in the blood stream. However, during the beginning (acute) phase of inflammation, particularly as a result of bacterial infection and some cancers, neutrophils are one of the first group of inflammatory cells to migrate toward the site of inflammation, firstly through the blood vessels, then through interstitial tissue, following chemical signals (such as Interleukin-8 (IL-8), Interferon-gamma (IFN-gamma), and C5a) in a process called chemotaxis. They are the predominant cells in pus, accounting for its whitish/yellowish appearance.

Neutrophils react within an hour of tissue injury and are the hallmark of acute inflammation.